Body Mass Index (BMI) Calculator

What is BMI?

Body Mass Index (BMI) is a person’s weight in kilograms divided by the square of height in meters. BMI is an inexpensive and easy screening method for weight category—underweight, healthy weight, overweight, and obesity.

For adults 20 years and older, BMI is interpreted using standard weight status categories that are the same for all ages and for both men and women.

BMI Categories

BMI is categorized as follows:

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5 to 24.9
• Overweight: BMI 25 to 29.9
• Obesity: BMI 30 or greater

These categories help identify potential weight-related health problems.

What is Ponderal Index?

The Ponderal Index (PI) is a measure of leanness (body mass per unit height) similar to BMI. The Ponderal Index is calculated as:

PI = weight (kg) / height (m)³

Unlike BMI, the Ponderal Index may be more accurate for people with very short or very tall stature. However, BMI remains the most widely used measure for health assessment.

Risks of High BMI

Higher BMI values are associated with increased risk of:

• Heart disease and stroke
• Type 2 diabetes
• High blood pressure
• Certain types of cancer
• Sleep apnea and breathing problems
• Osteoarthritis

Maintaining a healthy BMI can significantly reduce these risks.

Achieving Healthy Weight

To achieve and maintain a healthy weight:

• Eat a balanced diet rich in fruits and vegetables
• Engage in regular physical activity (150 min/week)
• Monitor portion sizes and limit processed foods
• Stay hydrated and limit sugary drinks
• Get adequate sleep and manage stress

Small, sustainable changes are more effective than drastic diets.

BMI Limitations

While BMI is a useful screening tool, it has limitations:

• Doesn’t directly measure body fat
• May overestimate body fat in athletes
• May underestimate body fat in older adults
• Doesn’t account for muscle mass or body composition

For a complete health assessment, consult with a healthcare provider.